Fuel feed system for recycling fuel

ABSTRACT

Disclosed herein is a fuel feeding system comprising a carburetor having fuel passage means communicating between a fuel nozzle and a fuel bowl and including a sharp-edged orifice, together with means for controllably admitting air into the fuel passage means. Also disclosed herein is a fuel feeding system in which &#39;&#39;&#39;&#39;ends&#39;&#39;&#39;&#39; or &#39;&#39;&#39;&#39;drains&#39;&#39;&#39;&#39; are recycled from the crankcase through a sharp-edged orifice into an engine cylinder.

United States Patent Turner et al.

[ Dec. 30, 1975 FUEL FEED SYSTEM FOR RECYCLING FUEL Inventors: Robert K.Turner, Waukegan;

Edgar Rose, Glencoe, both of I11.

Outboard Marine Corporation, Waukegan, 111.

Filed: Dec. 5, 1974 Appl. No.: 529,860

Related US. Application Data Continuation of Ser. No. 402,322, Oct. 1,1973, abandoned, which is a division of Ser. No. 228,775, Feb. 23, 1972,abandoned, which is a division of Ser. No. 17,729, March 9, 1970,abandoned.

Assignee:

US. Cl. 123/73 R; 123/73 A; 123/73 PP; 123/73 CB; 123/D1G. 2

Int. Cl. F0213 33/04 Field of Search 123/73 R, 73 A, 73 CB, 123/73 PP,DIG. 2

References Cited UNITED STATES PATENTS 6/1954 Watkins 123/73 A 2,717,5849/1955 Upton 123/73 R 2,718,866 9/1955 Kiekhaefer. 123/73 A 3,128,7484/1964 Goggi 123/73 R 3,132,635 5/1964 Heidner 123/73 A 3,528,395 9/1970Goggi 123/73 R 3,709,202 1/1973 Br0wn..... 123/73 R 3,730,149 5/1973Brown 123/73 R 3,800,753 4/1974 Sullivan et al..... 123/73 PD 3,815,5586/1974 Tenney 123/73 R Primary ExaminerWendell E. Burns Attorney, Agent,or Firm-Michael, Best & Friedrich 57 ABSTRACT Disclosed herein is a fuelfeeding system comprising a carburetor having fuel passage meanscommunicating between a fuel nozzle and a fuel bowl and including asharp-edged orifice, together with means for controllably admitting airinto the fuel passage means. Also disclosed herein is a fuel feedingsystem in which ends or drains are recycled from the crankcase through asharp-edged orifice into an engine cylinder.

1 Claim, 6 Drawing Figures US. Patent Dec. 30, 1975 Sheet 1 of23,929,111

I I A FUEL FEED SYSTEM FOR RECYCLING FUEL This application is acontinuation of our application Ser. No. 402,322 filed Oct. 1, 1973 andnow abandoned, which, in turn, is a division of application Ser. No.228,775 filed Feb. 23, 1972, and nowabanoned, which is a division ofapplication Ser. No. 17,729 filed Mar. 9, 1970, and now abandoned.

BACKGROUND OF THE INVENTION The invention relates generally to internalcombustion engines, and particularly to two-stroke internal combustionengines wherein lubricant is commonly, mixed with fuel. The inventionalso relates to fuel feeding arrangements for internal combustionengines generally.

Rough or uneven engine operation and even engine stalling can occur withpresent fuel feeding systems in response to changes in the viscosity ofthe fuel being supplied to the engine. Such changes and viscosity canoccur when high viscosity ends or drains collect in the crankcase of atwo cycle engine and are re-cycled into the fuel feeding system ordirectly into the cylinder or cylinders. Such viscosity change can alsooccur when switching from one source of fuel to another, andparticularly in connection with two-stroke engines, when changing fromone fuel-oil mixture to another, i.e., when there are differences inmixture ratio between the two mixture sources.

The I-Ieidner US. Pat. No. 3,132,635 discloses a two cylinder,two-stroke engine including one arrangement for pumping ends or drains,such as oil or the like, from the crankcases to the cylinders.

SUMMARY OF THE INVENTION The invention provides for a fuel feedingsystem for an internal combustion engine, which system is largelyindependent of variation in viscosity of the fuel being fed to theengine. In accordance with the invention, the fuel feeding systemincludes a sharp-edged orifice which under given pressure conditionswill supply a constant volume flow, notwithstanding changes in fuelviscosity. In arrangements where high viscosity ends or drains arere-cycled by being pumped into a carburetor bowl, employment of asharp-edged orifice between the bowl and the air-fuel induction passageor venturi section thereof will provide for smooth engine operationindependently of the amount of re-cycled high viscosity fuel.

In arrangements where high viscosity ends are re-cycled directly to acylinder, a sharp-edged orifice can be used to meter a substantiallyconstant volume flow to the cylinder independently of the viscosity ofthe ends.

Other objects and advantages of the invention willv become known byreference to the following description and the accompanying drawings inwhich:

Drawings incorporated in. the

FIG. 4 is an enlarged sectional view ofstill' another modifiedcarburetor which can be employed in the fuel feeding system of FIG. 1.

FIG. 5 is a schematic sectional view of another engine and fuel feedingsystem in accordance with the invention.

FIG. 6 is an enlarged sectional view of the sharpedged orifice which isincluded in the embodiment of FIG. 2 and which is similar to thesharp-edged orifices embodied in FIGS. 3 and '5.

GENERAL DESCRIPTION Shown in FIG. 1 of the drawings is a more or lessconventional, two cylinder, two-stroke engine 11 including separatecylinders 13 and 15 each having respective crankcase portions 17 and 19and respective pistons 21 and 23 connected by respective rods 25 and 27to a crankshaft 29 rotatably journaled in the crankcases 17 and 19. Theengine 11 also includes a fuel supply system 31 including a carburetor33 (See also FIG. 2) having an air-fuel induction passage 37 leading(See FIG. 1) through reed valves 39 and 41 .to the respective crankcases17 and 19.

The carburetor 33 can be generally of conventional construction, exceptas modified in accordance with the invention. As shown in FIG. 2, thecarburetor includes a frame or housing 43 which defines the air-fuelinduction passage 37 including a venturi section 47. The carburetorhousing also includes a fuel reservoir or bowl 49 into which fuel isadmitted in a conventional manner from a fuel line 51 leading from aremote fuel tank (not shown) in response to operation of a conventionalfloat valve 53. In turn, the reservoir 49 communicates with a main orhigh speed nozzle or jet 57 terminating in the venturi section 47 andthrough a conduit 59 with a relatively large void or cavity 61 fromwhich one or more secondary or idling nozzles or jets 63 communicatewith the air-fuel induction passage 37 downstream of the venturi section47. As has been the common practice, the secondary or idle nozzles 63are located in straddling relation to a throttle valve 67 when thethrottlevalve is closed and extend from the enlarged recess or void 61communicating with the receiver 49 through the conduit 59.

Shown schematically in FIG. 1 are re-cycling conduits 69 and 71 whichare respectively connected to the crankcases 17 and 19 in the area whereends or drains of high viscosity will normally tend to collect. Theconduits 69 and 7.1 are respectively provided with check valves 73 and77 to afford fluid flow from the crankcases I7 and 19 while alsopreventing return flow. As thus far described, the construction isentirely conventional as disclosed, for instance, in part, in the beforementioned I-Ieidner US. Pat. No. 3,132,635.

In accordance with the invention, means are provided for obtaininguniform fuel flow to the secondary nozzles 63, notwithstanding variationin fuel viscosity. In the disclosed construction, such means includes asharp-edged orifice 81 which is located in the void or cavity 61 betweenthe conduit 59 and the secondary nozzles 63.

The sharp-edged orifice 81 is provided by utilizing a relatively thinmetal plate or-partition 83 having therein the circular orifice 81 whichis relatively small (See FIG. 6) as compared to the over-all circularsize of the plate 83. One sharp-edged orifice in accordance with theinvention has a wall thickness of 0.002 inches and an orifice diameterof 0.020 and an orifice wall area to 3 orifice area ratio ofapproximately 1521. Such a sharpedged orifice is substantially viscosityindependent at given pressure conditions at least within the range offuel viscosity between 0.538 centistokes representing a gasoline to oilmixture of 50:1 and 3,850 centistokes representing a gasoline to oilmixture of 1:].

In operation, the suction in the air-fuel induction passage 37 createdby piston operation, causes sufficient fuel'flow through the conduit 59to fill the cross sectional area of the cavity 61 above the plate 83 andthereby provide a solid wall of fuel above the sharpedged orifice 81.

As used herein, the term sharp-edged" orifice is intended to refer to anorifice in a thin partition or wall. Preferably, the partition or wallis as thin as possible and the orifice is as large as possibleconsistent with maintaining a substantial ratio between the orifice areaand the over-all size of the wall or partition in which the orifice islocated. It is believed that substantial deviation' from the :1 ratiobetween the overall area of the orifice wall and the orifice area ispossible and that an orifice wall area to orifice area ratio as low as3:1 is practical. Although the orifice diameter is preferablygreaterthan the wall thickness, it is further believed that a sharp-edgeorifice in accordance with the invention can have an orifice diameter towall thickness ratio which can be as low as 1:1. Still further, itshould be noted that for best results, the orifice should be clear ofburrs or other irregularities.

Also in accordance with the invention, means are provided for regulatingthe quantity of fuel flow through the sharp-edged orifice 81 andparticularly at idle conditions. In the construction disclosed in FIG.2, such means is in the form of an air inlet passage or bleed 89communicating with the atmosphere and with the cavity 61 upstream of thesharp-edged orifice 81. Air flow through the passage 89 can becontrolled or metered by an adjustable needle valve 91 having a meteringpoint 93 extending'axially into a cylindrical portion 97 of the passage.

Air flow through the needle valve controlled passage 89 and into thecavity 61 upstream of the sharp-edged orifice 81 affects the pressurecondition downstream of the orifice 81 as compared to the pressurecondition upstream and therefor controls the quantity of fuel flowingthrough the orifice. Such fuel flow can be closely controlled bycontrolling the air flow through the passage and therefore the pressuredifferential between the upstream and downstream sides of the orificecan also be closely controlled. In this regard, increased flow of airthrough the passage 89 will reduce flow through the orifice 81, whilereducing the air flow through the passage 89 into the cavity 61 willincrease fuel flow through the orifice 81. Thus, adjustment of theneedle valve 91 can be employed to control the pressure differentialacross the sharp-edged orifice 81 and therefor the flow rate through theorifice 81, notwithstanding variation in the fuel viscosity.

Also in accordance with the invention, the conduits 69 and 71 leadingfrom the crankcases 17 and 19 are connected to the reservoir 49 fordelivery of ends or drains from the crankcases 17 and 19 to thecarburetor33. The conduits 69 and 71 can either constitute branches froma single conduit 99 which, as shown in FIGS. 1 and 2, flows into thereservoir 49 or both conduits 17 and 19 can be independently connectedto the reservoir 49. Because of the provision of the previouslymentioned check valves 73 and 77 and the movement LII 4 of the pistons21 and 23 relative to the crankcases 17 and 19, the pulsating pressuresproduced in the crankcases 17 and 19 will serve to pump fuel ends ordrains from the crankcases 17 and 19 to the reservoir 49, thus variablyaffecting the viscosity of the fuel in the reservoir 49.

Also in accordance with the invention, and in order to avoid adverselyaffecting carburetor operation, means are provided for relievingpressure which may accompany re-cycled fuel from the crankcases 17 and19. While various arrangements can be employed, in the disclosedconstruction, and as shown schematically in FIGS. 1 and 2, theconduit 99includes, adjacent to the carburetor 33, an inverted U-shaped portion111 having one leg 113 directly and immediately supplying fuel to thecarburetor reservoir 49 and having another leg 117 communicating withthe crankcases 17 and 19. At its top, the U-shaped portion 111communicates .with a vent line 119 to the atmosphere, which line 119relieves the fuel from any significant pressure condition prior topassage into the carburetor bowl or reservoir 49. While the pressureventing means has been disclosed in a schematic fashion and in aphysical location exterior to the carburetor housing 43, the pressureventing means can readily be bodily incorporated into the frame orhousing 43 of the carburetor 33.

Shown in FIG. 3 is a carburetor 133 which is also in accordance with theinvention, and which is essentially identical to the carburetor 33 shownin FIG. 2, except that the carburetor 133 includes an air bleed passage189 which communicates between the atmosphere and the downstream side ofa sharp-edged orifice 181. Adjustment of a needle valve 191 serves toeffect the pressure in the cavity 161 on the downstream side of theorifice 181 and permits control of the pressure differntial between theupstream and downstream sides of the orifice 181 so as to afford controlof fuel flow, notwithstanding viscosity variation. The arrangement shownin FIG. 3 is preferred over the arrangement shown in FIG. 2.

In the above two embodiments, the sharp-edged orifices 81 and 181 havebeen employed to meter fuel flow to the secondary nozzles and thereforto insure even engine operation at idling and at low speed operation,notwithstanding fuel viscosity variation. It is also in accordance withthe invention to control fuel flow to the main nozzle by means of asharp-edged orifice so as to contribute to smooth engine operation atspeeds above idling, notwithstanding fuel viscosity variation.Accordingly, there is shown in FIG. 4 another carburetor 233 which is inaccordance with the invention and which includes a frame or housing 243defining an air-fuel induction passage 237 including a venturi section247, and a fuel reservoir or bowl 249 having a fuel supply inlet 251controlled by a conventional float valve structure 253. The carburetor233 also includes an inlet 313 into the reservoir or bowl 249 forre-cycled fuel. An arrangement similar to that disclosed with respect toFIG. 2 can be employed to vent any pressure to which the re-cycled fuelmay be subject. Communicating with the fuel reservoir 249 is a fuelconduit or passage 256 which supplies fuel to a tubular main nozzle 257terminating in the venturi section 247 of the air fuel induction passage237 and which communicates through a secondary fuel conduit or passage259 with a series of secondary or idling nozzles or jets 263. Althoughother constructions could be employed, in the disclosed construction,the secondary fuel conduit 259 extends, in part, within the main.-n9zzle-27;.., In addition, the secondary fuel conduit 259 extends through ametering aperture 268 and communicates with a plugged void or cavity 261from which the secondary nozzles 263 extend. Control of the fuel flowrate to the secondary nozzles 263 from the conduit 259 is controlled bya needle valve 170 having a point 272 movable relative to the meteringaperture 268 to control the flow of fuel through the passage 259.

In order to avoid flow rate variation because of viscosity variation, toboth the main and secondary nozzles, a sharp-edged orifice 281 isprovided at the entrance to the passage 256 from the fuel bowl 259,i.e., at a point upstream of the communication between the passage 256and each of the lower end of the main nozzle 257 and the secondary fuelconduit 259 leading to the idle nozzles 263. While the orifice 281 isshown at the entrance to the passage 256, it should be understood thatthe orifice 281 could be located in the passage 256 upstream from thebeginning of the main nozzle 257 and of the secondary conduit 259leading to the idle nozzles 263.

Also provided is an air bleed arrangement permitting adjustment of thepressure differential between opposite sides of the orifice 281. Whilevarious arrangements can be employed, in the disclosed construction,there is shown in FIG. 4 an air tube 289 having one end 291 located inthe air-fuel induction passage 237 upstream from the venturi section 247and extending through a metering aperture 297 into the fuel passage 256at a point located between the sharp-edge orifice 281 and the junctureof the passage 256 with the main nozzle 257 and the secondary fuelconduit 259. As in the other embodiments, there is provided anadjustable needle valve 291 having a pointed end 293 movable relative tothe metering aperture 297 so as to control the amount of air which isdrawn into the passage 256 and thereby to affect the pressuredifferential between the opposite sides of the sharp-edged orifice 281.As has been previously explained, such pressure differen-v tial controlsthe flow rate through the orifice 281 independently of fuel viscosityvariation. It is to be noted that the air tube 289 leading to thepassage 256 has its inlet in the air-fuel induction passage 237 so as totend to provide increasing amounts of air with increasing.

suction in the air-fuel induction passage.

If desired, a sharp-edged orifice and an air venting or bleedingarrangement, such as already disclosed, can be located so as to controlfluid flow to the main nozzle only without affecting flow to thesecondary nozzle. Referring to FIG. 4, the secondary conduit 259 couldbe communicated with the reservoir 249 separately from the main nozzle257 and independently of the sharp-edged orifice controlling flow to themain nozzle, the length of the main nozzle 257 could be shortened and asharp-edged orifice could be located at the point 300 beneath theshortened lower end of the main nozzle. In addition, an air bleed couldbe introduced between the sharp-edged orifice and the shortened lowerend of the main nozzle.

In general, in all of the above disclosed embodiments, there is a wallof fuel behind the sharp-edged orifice which, together with the orificestructure, will result in a given flow independently of the viscosityvariation and in accordance with the pressure differential exist-,

so, asto control t h e pressure variation between oppos- .ing sides,whereby to control fuel flow at an essentially constant value undergiven pressure conditions, notwithstanding viscosity variation.

Shown in FIG. 5 is still another embodiment of the invention.Specifically, disclosed in FIG. 5 is a twostroke engine 401 including acylinder 403 having a crankcase 405 and a piston 407 operable in thecylinder 403 and connected by a rod 409 to a crankshaft 411 journaled inthe crankcase 405. An air-fuel mixture is supplied to the crankcase 405from a carburetor 431 and through a check or reed valve 433. Fuel-airmixture flow from the crankcase 405 to the cylinder 403 is primarilythrough a transfer passage 435. In addition, drains or ends are drainedthrough a check valve 437 to a conduit 439 leading from the crankcase405.

In accordance with the invention, the drains are arranged to return tothe cylinder 403 at a point 441 adjacently spaced from the transferpassage 435 toward the head end of the cylinder 403, which drains arereturned through a sharp-edged orifice 481 in an enlarged well 483 so asto provide for substantially uniform flow from the conduit 439 to thecylinder 403 in response to the pressure condition created in theconduit 439 by the pumping action of the crankcase 405 and when theconduit 439 is open to the cylinder 403 as when the piston 407 isadjacent bottom dead center.

In some instances, where large quantities of drains are produced, it maybe desirable to route some of the drains to a carburetor constructed ingeneral accordance with FIGS. 2, 3 and 4, while routing another portionof the drains directly back to the cylinder as shown, for instance, inFIG. 5.

In addition to being applicable to two-stroke engines, the invention isapplicable to four-stroke engines which may be subject to variation infuel viscosity as, for instance, when changing between kerosene togasoline upon variation in engine speed. Still further, it should bepointed out that the advantages of using a sharpedged orifice with orwithout an air metering valve, are not limited to applications inconnection with re-cycled fuels. Sharp-edged orifices in accordance withthe invention are also applicable for use with fresh" fuels andparticularly where variation in the viscosity of the fresh" fuel mixturecan occur. In all of the above embodiments, the drains can be pumped bymeans other than the disclosed two-stroke crankcase pumping action.

It should also be pointed out that just as a carburetor is calibrated toa particular engine, the size of the sharp-edged orifice will alsonormally have to be calibrated to a particular engine. Still further, itis possible to use several small orifices in a single partition or wallin order to get the desired total amount of flow.

Various of the features of the invention are set forth in the followingclaims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A two-cycle internal engine including a crankcase having a portion inwhich drains accumulate, a cylinder extending from said crankcase, apiston movable in said cylinder and relative to said crankcase, atransfer passage communicating, subject to piston operation, betweensaid crankcase and said cylinder, a conduit communicating with saidcrankcase portion, valve means in said conduit preventing flow to saidcrankcase 7 and permitting flow from said crankcase, said conduitcommunicating with said cylinder independently of said transfer passage.

Dedication 3,929,111.R0bert K. Turner, Waukegan; Edgar Rose, Glencoe,Ill. FUEL FEED SYSTEM FOR RECYCLING FUEL. Patent dated Dec. 30, 1975.Dedication filed Apr. 10, 1984, by the assignee, Outboard Marine Corp. vHereby dedicates to the Public the remaining term of said patent.

[Official Gazette July 3, 1984.]

1. A two-cycle internal engine including a crankcase having a portion inwhich ''''drains'''' accumulate, a cylinder extending from saidcrankcase, a piston movable in said cylinder and relative to saidcrankcase, a transfer passage communicating, subject to pistonoperation, between said crankcase and said cylinder, a conduitcommunicating with said crankcase portion, valve means in said conduitpreventing flow to said crankcase and permitting flow from saidcrankcase, said conduit communicating with said cylinder independentlyof said transfer passage.